1. Field of the Invention
The present invention relates to a light diffusing laminated resin sheet having excellent face impact resistance and high Young's modulus in flexure.
This laminated resin sheet is suitably used for lighting covers, light diffusing sheets on the surface of the liquid crystal layer of a display, illumination sign boards and the like.
2. Description of the Related Art
Usually, for imparting light diffusing property to a methyl methacrylate resin and styrene resin, there are added fine particles of inorganic material or polymer material having different refractive index from those of the methyl methacrylate resin and styrene resin which are base materials.
Thus obtained resin sheets having light scattering property are often used for lighting covers, illumination signboards and light diffusing sheets on the surface of the liquid crystal layer of a display.
These resin sheets are sometimes required to have excellent impact resistance, particularly excellent face impact resistance depending on the use, because these resin sheets are sometimes cracked.
For improving face impact resistance, for example, Japanese Patent Application Laid-Open (JP-A) No. 8-198,976 discloses a technology for allowing a rubber component to be contained in a light diffusing resin sheet.
Recently, resin materials having light diffusing property are often molded at high draw magnification particularly in the field of a lighting cover. With the development in molding technology, the protruded portion at corner of a lighting cover becomes large and the thickness of a lighting cover does not increase so much, therefore, there occurs a problem that a lighting cover is broken in manufacturing and transportation.
The light diffusing resin sheet described in JP-A No. 8-198,976 has a defect that a lot of rubber components should be contained for improving face impact resistance, leading to a disadvantage in cost and decrease in the Young's modulus in flexure of the resin sheet, therefore, the sheet is not suitable for a large molded article.
The present inventors have intensively studied about a light diffusing resin sheet having excellent face impact resistance. As a result, the present inventors have found that a light diffusing resin sheet having excellent face impact resistance and high Young's modulus in flexure can be obtained by laminating a resin layer into which a light diffusing agent is dispersed and a resin layer into which a specific impact resistance component. Thus the present invention has been accomplished.